[PATCH v2] net/ice: fix statistics read error

[Zhichao Zeng]

The statistics contain 40 bits. The lower 32 bits are read first, followed
by the upper 8 bits.

In some cases, after reading the lower 32 bits, a carry occurs from
the lower bits, which causes the final statistics to be incorrect.

This commit fixes this issue.

Fixes: a37bde56314d ("net/ice: support statistics")
Cc: stable at dpdk.org

Signed-off-by: Zhichao Zeng <zhichaox.zeng at intel.com>

---
v2: replace single retries with loops
---
 drivers/net/intel/ice/ice_ethdev.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/net/intel/ice/ice_ethdev.c b/drivers/net/intel/ice/ice_ethdev.c
index 4669eba7c7..016b25c63a 100644
--- a/drivers/net/intel/ice/ice_ethdev.c
+++ b/drivers/net/intel/ice/ice_ethdev.c
@@ -6351,10 +6351,16 @@ ice_stat_update_40(struct ice_hw *hw,
 		   uint64_t *stat)
 {
 	uint64_t new_data;
+	uint32_t lo_old, hi, lo;
 
-	new_data = (uint64_t)ICE_READ_REG(hw, loreg);
-	new_data |= (uint64_t)(ICE_READ_REG(hw, hireg) & ICE_8_BIT_MASK) <<
-		    ICE_32_BIT_WIDTH;
+	do {
+		lo_old = ICE_READ_REG(hw, loreg);
+		hi = ICE_READ_REG(hw, hireg);
+		lo = ICE_READ_REG(hw, loreg);
+	} while (lo_old > lo);
+
+	new_data = (uint64_t)lo;
+	new_data |= (uint64_t)(hi & ICE_8_BIT_MASK) << ICE_32_BIT_WIDTH;
 
 	if (!offset_loaded)
 		*offset = new_data;
@@ -6363,10 +6369,8 @@ ice_stat_update_40(struct ice_hw *hw,
 		*stat = new_data - *offset;
 	else
 		*stat = (uint64_t)((new_data +
-				    ((uint64_t)1 << ICE_40_BIT_WIDTH)) -
-				   *offset);
-
-	*stat &= ICE_40_BIT_MASK;
+					((uint64_t)1 << ICE_32_BIT_WIDTH))
+				   - *offset);
 }
 
 /**
-- 
2.34.1